Preliminary Tests on the Biological Control of some Root Rot Fungal Pathogens in Sugar Beet In Vitro

The use of biological control is becoming a common practice in plant production. One overlooked group of organisms potentially suitable for biological control are Rhizoctonia-like (Rh-like) fungi. Some of them are capable of forming endophytic associations with a large group of higher plants as well as mycorrhizal symbioses. Various benefits of endophytic associations were proved, including amelioration of devastating effects of pathogens such as Fusarium culmorum. The advantage of Rh-like endophytes over strictly biotrophic mycorrhizal organisms is the possibility of their cultivation on organic substrates, which makes their use more suitable for production. We focused on abilities of five Rh-like fungi isolated from orchid mycorrhizas, endophytic fungi Serendipita indica, Microdochium bolleyi and pathogenic Ceratobasidium cereale to inhibit the growth of pathogenic F. culmorum or Pyrenophora teres in vitro. We also analysed their suppressive effect on wheat infection by F. culmorum in a growth chamber, as well as an effect on barley under field conditions. Some of the Rh-like fungi affected the growth of plant pathogens in vitro, then the interaction with plants was tested. Beneficial effect was especially noted in the pot experiments, where wheat plants were negatively influenced by F. culmorum. Inoculation with S. indica caused higher dry shoot biomass in comparison to plants treated with fungicide. Prospective for future work are the effects of these endophytes on plant signalling pathways, factors affecting the level of colonization and surviving of infectious particles.

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Biological control of strawberry crown rot, root rot and grey mould by the beneficial fungus Aureobasidium pullulans

BioControl ◽

10.1007/s10526-021-10083-w ◽

2021 ◽

Author(s):

Mudassir Iqbal ◽

Maha Jamshaid ◽

Muhammad Awais Zahid ◽

Erik Andreasson ◽

Ramesh R. Vetukuri ◽

...

Keyword(s):

Root Rot ◽

Fungal Pathogens ◽

Aureobasidium Pullulans ◽

Grey Mould ◽

Lesion Size ◽

Plant Diseases ◽

Crown Rot ◽

Whole Plants

AbstractUtilization of biocontrol agents is a sustainable approach to reduce plant diseases caused by fungal pathogens. In the present study, we tested the effect of the candidate biocontrol fungus Aureobasidium pullulans (De Bary) G. Armaud on strawberry under in vitro and in vivo conditions to control crown rot, root rot and grey mould caused by Phytophthora cactorum (Lebert and Cohn) and Botrytis cinerea Pers, respectively. A dual plate confrontation assay showed that mycelial growth of P. cactorum and B. cinerea was reduced by 33–48% when challenged by A. pullulans as compared with control treatments. Likewise, detached leaf and fruit assays showed that A. pullulans significantly reduced necrotic lesion size on leaves and disease severity on fruits caused by P. cactorum and B. cinerea. In addition, greenhouse experiments with whole plants revealed enhanced biocontrol efficacy against root rot and grey mould when treated with A. pullulans either in combination with the pathogen or pre-treated with A. pullulans followed by inoculation of the pathogens. Our results demonstrate that A. pullulans is an effective biocontrol agent to control strawberry diseases caused by fungal pathogens and can be an effective alternative to chemical-based fungicides.

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Sensitivity of Rhizoctonia solani AG-2-2 from Sugar Beet to Fungicides

Plant Disease ◽

10.1094/pdis-04-16-0525-re ◽

2016 ◽

Vol 100 (12) ◽

pp. 2427-2433 ◽

Cited By ~ 4

Author(s):

Sahar Arabiat ◽

Mohamed F. R. Khan

Keyword(s):

Sugar Beet ◽

Rhizoctonia Solani ◽

Root Rot ◽

The United States ◽

Damping Off ◽

Growth Assay ◽

The Mean ◽

Crown And Root Rot ◽

Mean Concentration

Rhizoctonia damping-off and crown and root rot caused by Rhizoctonia solani are major diseases of sugar beet (Beta vulgaris L.) worldwide, and growers in the United States rely on fungicides for disease management. Sensitivity of R. solani to fungicides was evaluated in vitro using a mycelial radial growth assay and by evaluating disease severity on R. solani AG 2-2 inoculated plants treated with fungicides in the greenhouse. The mean concentration that caused 50% mycelial growth inhibition (EC50) values for baseline isolates (collected before the fungicides were registered for sugar beet) were 49.7, 97.1, 0.3, 0.2, and 0.9 μg ml−1 and for nonbaseline isolates (collected after registration and use of fungicides) were 296.1, 341.7, 0.9, 0.2, and 0.6 μg ml−1 for azoxystrobin, trifloxystrobin, pyraclostrobin, penthiopyrad, and prothioconazole, respectively. The mean EC50 values of azoxystrobin, trifloxystrobin, and pyraclostrobin significantly increased in the nonbaseline isolates compared with baseline isolates, with a resistant factor of 6.0, 3.5, and 3.0, respectively. Frequency of isolates with EC50 values >10 μg ml−1 for azoxystrobin and trifloxystrobin increased from 25% in baseline isolates to 80% in nonbaseline isolates. Although sensitivity of nonbaseline isolates of R. solani to quinone outside inhibitors decreased, these fungicides at labeled rates were still effective at controlling the pathogen under greenhouse conditions.

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Variations in Pathogenicity of Three Different Forms of Rhizoctonia Inoculum and Assessment of Cultivar Resistance of Sugar Beet

Journal of Pathology & Microbiology ◽

10.26420/jpatholmicrobiol.2021.1019 ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

Haque ME ◽

◽

Parvin MS ◽

Keyword(s):

Seed Germination ◽

Sugar Beet ◽

Root Rot ◽

Large Scale ◽

Culture Media ◽

Damping Off ◽

Require Time ◽

Time Space ◽

The Usa

Rhizoctonia solani causes pre-emergence and post-emergence damping-off, as well as crown and root rot of sugar beet (Beta vulgaris L.), which significantly affects the yield returns in the USA and Europe. The pathogen overwinters as sclerotia or melanized mycelium. Traditionally, the resistance of cultivars to R. solani is evaluated by scoring disease reactions at the crowns and roots of older seedlings, thus resistance is not evaluated during seed germination. Moreover, earlier studies evaluated cultivars resistance to R. solani using colonized whole barley or wheat grains which, unlike sclerotia, are artificial inocula of the pathogen that require time, space and technical know-how to produce. Moreover, colonized grains are prone to contamination with other pathogens, consumed by rodents/birds while applied in the field, and are often uneconomic. Considering those limitations, a study was undertaken (1) to develop in vitro methods to generate large-scale sclerotia, (2) to compare pathogenic potentials of sclerotia, mycelia, and colonized barley grains for optimization of dampingoff assays, and (3) to evaluate Rhizoctonia resistance of selected commercial cultivars during the seed germination phase. Comparing six different culture media, we found that R. solani had the highest radial growth (8.9 ± 0.04, cm³) at 8-days and the maximum number of sclerotia produced (203 ± 4.6) at 28-days in CV8 medium. We demonstrated significant differences in pathogenicity of the three different forms of R. solani inocula and susceptibility of cultivars to preand post-emergence damping-off. The highest pre-emergence damping-off and root rot were observed with sclerotia, and the highest post-emergence dampingoff was recorded with both sclerotial and colonized barley inocula. In addition, varietal differences in susceptibility to pre- and post-emergence damping-off were noted. The highest pre-emergence damping-off was recorded on cv Crystal 101RR and lowest in Maribo MA 504. The highest post-emergence damping-off was recorded on BTS 8500 and the lowest in Crystal 467. The maximum mean root rot was observed in BTS 8500, BTS 8606, and Crystal 101R. Our studies demonstrated that sclerotia serve as efficient natural inocula, reemphasized that host-pathogen interactions differ at the early vs. late stages of sugar beet growth, and highlighted the need to reevaluate commercial sugar beet cultivars for resistance at the seed germination stage.

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Secondary Metabolite- and Endochitinase-Dependent Antagonism toward Plant-Pathogenic Microfungi of Pseudomonas fluorescens Isolates from Sugar Beet Rhizosphere

Applied and Environmental Microbiology ◽

10.1128/aem.64.10.3563-3569.1998 ◽

1998 ◽

Vol 64 (10) ◽

pp. 3563-3569 ◽

Cited By ~ 113

Author(s):

Mette Neiendam Nielsen ◽

Jan Sørensen ◽

Johannes Fels ◽

Hans Christian Pedersen

Keyword(s):

Biological Control ◽

Cell Wall ◽

Sugar Beet ◽

Pseudomonas Fluorescens ◽

Secondary Metabolite ◽

Pythium Ultimum ◽

Medium Composition ◽

Fungal Antagonism ◽

Lipopeptide Antibiotic

ABSTRACT Forty-seven isolates representing all biovars of Pseudomonas fluorescens (biovars I to VI) were collected from the rhizosphere of field-grown sugar beet plants to select candidate strains for biological control of preemergence damping-off disease. The isolates were tested for in vitro antagonism toward the plant-pathogenic microfungi Pythium ultimum and Rhizoctonia solani in three different plate test media. Mechanisms of fungal inhibition were elucidated by tracing secondary-metabolite production and cell wall-degrading enzyme activity in the same media. Most biovars expressed a specific mechanism of antagonism, as represented by a unique antibiotic or enzyme production in the media. A lipopeptide antibiotic, viscosinamide, was produced independently of medium composition by P. fluorescens bv. I, whereas the antibiotic 2,4-diacetylphloroglucinol was observed only in glucose-rich medium and only in P. fluorescens bv. II/IV. Both pathogens were inhibited by the two antibiotics. Finally, in low-glucose medium, a cell wall-degrading endochitinase activity in P. fluorescens bv. I, III, and VI was the apparent mechanism of antagonism toward R. solani. The viscosinamide-producing DR54 isolate (bv. I) was shown to be an effective candidate for biological control, as tested in a pot experiment with sugar beet seedlings infested with Pythium ultimum. The assignment of different patterns of fungal antagonism to the biovars of P. fluorescens is discussed in relation to an improved selection protocol for candidate strains to be used in biological control.

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The in vitro inhibition of Phytophthora clandestina by some rhizobia and the possible role of Rhizobium trifolii in biological control of Phytophthora root rot of subterranean clover

Australian Journal of Agricultural Research ◽

10.1071/ar99047 ◽

1999 ◽

Vol 50 (8) ◽

pp. 1469 ◽

Cited By ~ 5

Author(s):

S. Simpfendorfer ◽

T. J. Harden ◽

G. M. Murray

Keyword(s):

Biological Control ◽

Root Rot ◽

Subterranean Clover ◽

Trifolium Subterraneum ◽

Root Disease ◽

Rhizobium Trifolii ◽

Biological Control Agents ◽

Control Activity ◽

Phytophthora Root Rot

The interaction between 29 isolates of Rhizobium and the in vitro growth of 3 strains of Phytophthora clandestina was investigated to determine the potential of these bacteria as biological control agents against root rot of subterranean clover (Trifolium subterraneum L.). The biological control activity of Rhizobium on the severity of root disease in seedlings was also investigated under glasshouse conditions. Thirteen of the 29 Rhizobium isolates caused significant reductions in the hyphal growth of the 3 P. clandestina isolates examined. Inoculation of seedlings with Rhizobium trifolii reduced the severity of root disease by 14–58% with corresponding increases in dry matter production of 20–73%. These results indicate that Rhizobium species have potential as biological control agents against the root rot of T. subterraneum seedlings caused by P. clandestina.

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Biological control of damping-off of sugar-beet and cotton with Chaetomium globosum or a fluorescent Pseudomonas sp.

Canadian Journal of Microbiology ◽

10.1139/m88-104 ◽

1988 ◽

Vol 34 (5) ◽

pp. 631-637 ◽

Cited By ~ 25

Author(s):

D. Walther ◽

D. Gindrat

Keyword(s):

Biological Control ◽

Sugar Beet ◽

Seed Treatment ◽

Pythium Ultimum ◽

Chaetomium Globosum ◽

Pseudomonas Sp ◽

Damping Off ◽

Antifungal Metabolites ◽

Fluorescent Pseudomonas

Seed treatment with ascospores of Chaetomium globosum reduced damping-off of sugar-beet caused by seed-borne Phoma betae and soil-borne Pythium ultimum or Rhizoctonia solani in growth chamber experiments. Seed treatment with a fluorescent Pseudomonas sp. controlled Ph. betae and P. ultimum but not R. solani. Coating cotton seeds with ascospores controlled P. ultimum and R. solani damping-off. In some experiments, biological seed treatments were equally or more effective than seed treatment with captan. However, greater variability in disease control occurred with the antagonists than with captan. Fifty percent of freshly harvested ascospores of C. globosum germinated in 8 h on water agar. When ascospores were stored under air-dried conditions for 3 days to 2.5 years, germination increased to > 90%. Under same storage conditions, survival of Pseudomonas sp. was detected after 4 months. Antagonistic activities observed in vitro were hyphal coiling of C. globosum on R. solani, and mycostasis was induced by C. globosum or Pseudomonas sp. on agar and soil. The presumed cause of mycostasis is the diffusible antifungal metabolites which may also be involved in the biological control of damping-off.

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Epidemiological analysis of the effects of biofumigation for biological control of root rot in sugar beet

Plant Pathology ◽

10.1111/j.1365-3059.2012.02618.x ◽

2012 ◽

Vol 62 (1) ◽

pp. 69-78 ◽

Cited By ~ 10

Author(s):

N. Motisi ◽

S. Poggi ◽

J. A. N. Filipe ◽

P. Lucas ◽

T. Doré ◽

...

Keyword(s):

Biological Control ◽

Sugar Beet ◽

Root Rot ◽

Epidemiological Analysis

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Control of root rot (Phytophthora cinnamomi) in avocado (Persea Americana) with bioagents

Summa Phytopathologica ◽

10.1590/0100-5405/192195 ◽

2020 ◽

Vol 46 (3) ◽

pp. 205-211

Author(s):

Ciro Hideki Sumida ◽

Lucas Henrique Fantin ◽

Karla Braga ◽

Marcelo Giovanetti Canteri ◽

Martin Homechin

Keyword(s):

Biological Control ◽

Root Rot ◽

Phytophthora Cinnamomi ◽

Persea Americana ◽

Field Conditions ◽

In Vitro Tests ◽

Trichoderma Spp ◽

Maize Cultivation ◽

Antagonistic Potential

ABSTRACT Despite the favorable edaphoclimatic conditions for avocado production in Brazil, diseases such as root rot caused by the pathogen Phytophthora cinnamomi compromise the crop. With the aim of managing root rot in avocado, the present study aimed to evaluate chemical and biological control with isolates of Trichoderma spp. and Pseudomonas fluorescens. Thus, three assays were conducted to assess: (i) mycelial inhibition of P. cinnamomi by isolates of Trichoderma spp. and P. fluorescens from different crop systems; (ii) effect of autoclaved and non-autoclaved metabolites of P. fluorescens, and (iii) chemical or biological treatment of avocado seedlings on the control of root rot under field conditions. The isolates of Trichoderma spp. from maize cultivation soil and the commercial products formulated with Trichoderma presented greater antagonism (p <0.05) to the pathogen P. cinnamomi in the in vitro tests. Similarly, non-autoclaved metabolites of P. fluorescens presented antagonistic potential to control P. cinnamomi. Under field conditions, the fungicide metalaxyl and the bioagents showed effectiveness in controlling P. cinnamomi, as well as greater root length and mass. Results demonstrated potential for the biological control of avocado root rot with Trichoderma spp. and P. fluorescens.

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Biological Control of Pathogens Causing Root Rot Complex in Field Pea Using Clonostachys rosea Strain ACM941

Phytopathology ◽

10.1094/phyto.2003.93.3.329 ◽

2003 ◽

Vol 93 (3) ◽

pp. 329-335 ◽

Cited By ~ 49

Author(s):

Allen G. Xue

Keyword(s):

Root Rot ◽

Seed Treatment ◽

Fungal Pathogens ◽

Seedling Emergence ◽

Field Pea ◽

Mycosphaerella Pinodes ◽

Limiting Factor ◽

Aphanomyces Euteiches ◽

Clonostachys Rosea

Pea root rot complex (PRRC), caused by Alternaria alternata, Aphanomyces euteiches, Fusarium oxysporum f. sp. pisi, F. solani f. sp. pisi, Mycosphaerella pinodes, Pythium spp., Rhizoctonia solani, and Sclerotinia sclerotiorum, is a major yield-limiting factor for field pea production in Canada. A strain of Clonostachys rosea (syn. Gliocladium roseum), ACM941 (ATCC 74447), was identified as a mycoparasite against these pathogens. When grown near the pathogen, ACM941 often was stimulated to produce lateral branches that grew directly toward the pathogen mycelium, typically entwining around the pathogen mycelium. When applied to the seed, ACM941 propagated in the rhizosphere and colonized the seed coat, hypocotyl, and roots as the plant developed and grew. ACM941 significantly reduced the recovery of all fungal pathogens from infected seed, increased in vitro seed germination by 44% and seedling emergence by 22%, and reduced root rot severity by 76%. The effects were similar to those of thiram fungicide, which increased germination and emergence by 33 and 29%, respectively, and reduced root rot severity by 65%. When soil was inoculated with selected PRRC pathogens in a controlled environment, seed treatment with ACM941 significantly increased emergence by 26, 38, 28, 13, and 21% for F. oxysporum f. sp. pisi, F. solani f. sp. pisi, M. pinodes, R. solani, and S. sclerotiorum, respectively. Under field conditions from 1995 to 1997, ACM941 increased emergence by 17, 23, 22, 13, and 18% and yield by 15, 6, 28, 6, and 19% for the five respective pathogens. The seed treatment effects of ACM941 on these PRRC pathogens were greater or statistically equivalent to those achieved with thiram. Results of this study suggest that ACM941 is an effective bioagent in controlling PRRC and is an alternative to existing chemical products.

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